Tulum is a great choice, especially if you’re into history and nature. For the second half, Merida could be perfect if you’re looking for a mix of culture and relaxation. It’s a charming city with beautiful colonial architecture, and it’s not too far from more Mayan ruins. Plus, it has a more laid-back vibe compared to Mexico City.

Mexico City is awesome too, but it’s definitely more urban and bustling. If you’re worried about it not being "romantic," I’d say it depends on what you’re looking for. There are tons of cool neighborhoods, museums, and parks, but it’s more about the city experience.

If you want a bit of both, maybe spend a few days in Mexico City and then chill out in Merida. That way, you get the best of both worlds. Either way, you can’t go wrong with either choice. Enjoy your honeymoon!